Behind most online activities engaged in today are large groups of computers closely networked together at facilities commonly referred to as data centers. Whether it is search engines operated by large Internet search engine companies such as Google, online social networking sites such as Facebook or online retailer such as Amazon.com, behind all of their online services are large data centers often consisting of tens of thousands of computers interconnected by means of hundreds of networking components. As new online applications and services grow, the ubiquity, size, complexity and cost of such data centers will continue to grow.
Typical network architecture for data includes of routers and/or switches interconnected in a hierarchical manner using a tree like topology. Computers are typically connected to lower-end switches (edge switches) at the leaves of the network tree by means of 1 Gbps Ethernet interfaces. Closer to the roots of the tree where data traffic get aggregated, higher performance switches with higher data rate interfaces (10 Gbps or more) are deployed. Although most data centers today are constructed using similar scheme, they suffer form the following fundamental limitations, as discussed by M. Al-Fares, A. Loukissas and A. Vandat. A Scalable in Commodity Data Center Network Architecture, SIGCOMM'08, Aug. 17-22, 2008.